If you’re a refugee from Aperture, see my Moving from Aperture to Lightroom page

It’s been obvious for a while that Apple couldn’t be making money from Aperture and that they were no longer investing in developing new versions, but finally the sword has fallen. Apple To Cease Development Of Aperture:

With the introduction of the new Photos app and iCloud Photo Library, enabling you to safely store all of your photos in iCloud and access them from anywhere, there will be no new development of Aperture. When Photos for OS X ships next year, users will be able to migrate their existing Aperture libraries to Photos for OS X.

Even before that announcement, consistently the most-visited page on this site was my Moving from Aperture to Lightroom. If that’s what brought you here, moving to Lightroom is not too difficult a process. I’d just say that with these things the devil is always in the detail, so as well as reading the article I would encourage Aperture refugees to read the comments where some of the individual insights might prove particularly helpful.